Chicago has won 15 in a row at Wrigley Field when Lieber has started.
Lieber (4-0) improved to 13-0 at Wrigley, dating to last May 24 -- the date of his one-hitter against Cincinnati.
It is the longest winning stretch for a pitcher at Wrigley since the early 1930s, when the club won 16 straight starts by Lon Warneke from May 27, 1932 to April 18, 1933. Warneke went 13-0 in that span.
Displaying a sharp slider and his usual excellent control, Lieber pitched eight innings and allowed one run and six hits with no walks and four strikeouts. He threw just 79 pitches, 59 of which were strikes, and went to three balls on just one batter.
Hernandez (4-1) was almost as good, yielding two runs and seven hits in eight innings with one walk and three strikeouts.
Antonio Alfonseca yielded a leadoff double to Jeff Kent in the ninth inning but retired the next three batters for his fourth save.
Kent failed to execute a double play in the bottom of the eighth inning, allowing the Cubs to snap a 1-1 tie. Joe Girardi led off the inning with a single, was sacrificed to second by pinch-hitter Augie Ojeda and moved to third on a single by Corey Patterson, who went three for three.
Delino DeShields then hit a grounder up the middle, which was fielded by Kent, who backhanded the ball from his second base position. But Kent stumbled past the base and had to retreat to tag it before firing to first, where DeShields easily beat the throw as Girardi scored.
Sosa won his personal battle with Giants slugger Barry Bonds, hitting a solo home run in the fourth inning to give the Cubs a 1-0 lead. Sosa hit two homers in the three-game series while Bonds went none for seven.
The Giants scored their only run off Lieber in the seventh, when J.T. Snow doubled, was sacrificed to third by Benito Santiago and came home on a sacrifice fly by Pedro Feliz.